The invention relates to devices used in the control and handling of liquid chemicals including acids, solvents, bases, photo-resists, dopants, inorganics, organics, biological solutions, pharmaceuticals, radioactive chemicals, and liquids commonly used in the semiconductor industry. In particular, the invention relates to fluid control devices which employ a bellows in handling the liquid chemicals.
Bellows have had numerous applications in the area of fluid control. Bellows have been used by devices which pump liquids, which regulate the flow of liquids, and which measure differential pressures. In certain industries, particularly the semiconductor industry, it is essential that the liquid chemical avoid contamination. Contact with metallic componentry may cause ionic contamination. In addition, removal of submicron particulate within the devices is extremely difficult. These particulates end up in the liquid chemicals and affect their purity. To prevent contamination of the liquid chemicals, inert thermoplastic materials, such as polytetrafluoroethylene (PTFE) are used in the construction of liquid chemical handling devices.
Forming bellows from thermoplastic materials is a tedious, expensive, and time-consuming process. Currently, bellows are formed from PTFE by machining or molding both an inside and outside surface of the PTFE to form convolutes on both the inside and outside surface of the PTFE. The convolutes, which give the PTFE bellows its compressibility, alternate between the inside and outside surfaces. Because bellows used in such liquid handling devices are very small, each convolute typically being 2/10 of an inch wide, machining both sides of the PTFE to form a bellows is difficult.